Efficient and accurate data presentation format for radars is often sought. A rotating antenna of a radar transmits pulses at regular intervals. A radar receiver converts the reflected pulses, or “returns” and displays them on a circular-shaped area on a monitor or display. This display is known as Plan Position Indicator (PPI) and gives the plan view of the distribution of radar scatterer parameters in an area around the antenna. PPI may, for example, be suitable for observing the evolution of weather phenomena including fast-developing phenomena.
Radar scan data may be converted to a 2-D format appropriate for presentation in polar coordinates with respect to a radar location. In a centered PPI mode, the antenna location is mapped at the center of the circular area of the display. In an offset PPI mode, the antenna location is represented at an offset from the center of the display area. The offset may be in an x-direction or y-direction or both x- and y-directions.
An analog PPI display includes a bright radial line, made visible due to bombardment of electron beam on the phosphor coating on a cathode ray tube (CRT), rotated around the circular face of CRT. Due to its persistence property, the phosphor coating continues to emit light for a few seconds after being activated. The entire display is refreshed by a next cycle of bombardment of electron beam. The PPI display is refreshed once per revolution of the radar antenna, and depends on the revolution rate of the radar antenna.
Radar spoking includes periodic flashes of the rotating time base or sweep on a radial display. The radar spoking may be caused by mutual interference or jamming.
A Liquid Crystal Display (LCD) monitor used for the PPI display utilizes the characteristics of crystals when electricity is applied to them. A matrix of these crystals constitutes the display, in which colors can be turned on or off by the application of current. The LCD monitor may consume less energy, and less physical space compared to a CRT display monitor. The resolution of LCD screens may be fixed, wherein the number of pixels that can be displayed on LCD monitor depends on the number of crystals of the matrix.
Near the radar site there is often ground clutter. Ground clutter may be substantially removed by using appropriate electronic filters. However, such filters may also remove parts of desirable signals. In the beam with the lowest elevation angle, PPI clutter is often so strong that filtering also removes useful signals resulting in a gap. For PPI scanning at higher elevation angles, the beam may overshoot precipitation, partly or totally, and thereby not detect the precipitation.